The present invention relates to railroad freight cars and in particular to an articulated multi-unit freight car for carrying motor vehicles on multiple levels.
Railroad freight cars have long been used for transporting newly manufactured automobiles long distances from the point of manufacture or a port of arrival to cities where dealerships are located or where the automobiles are reloaded onto trucks for moving the automobiles over highways to the locations of dealerships. In order for such railroad freight cars to be most economical it is desirable to carry a maximum number of motor vehicles on each railroad car, but it is also desired to be able to carry several different types of motor vehicles on each car and to be able to reconfigure the railroad freight car to carry such different types of vehicles without undue difficulty.
It is known to adjust load-carrying decks in motor vehicle-carrying railroad cars to facilitate carrying different types of motor vehicles, but provisions for making such adjustments in the past have been unsatisfactory.
Not only is it desired to carry a maximum number of automobiles or other motor vehicles on each railroad car, it is also desired to keep the center of gravity of a loaded car as low as possible, to promote lateral stability of the loaded railroad car. Railroad cars are restricted in size to fit within clearance envelopes established by agreements reached among railroads in order to avoid collisions between trains on adjacent tracks and to ensure that all cars fit within the clearances available along the rail lines at places such as bridges and tunnels.
In order to avoid pilferage or vandalism of motor vehicles and to protect motor vehicles from airborne hazards, many railroad freight cars designed to carry motor vehicles are enclosed and include roofs and end doors. The height of such a car, including its roof, is limited by the applicable clearance envelope. In order to have a maximum of height available within the confined space inside such a railroad freight car, then, it is desired for the structure of its roof to be as shallow as practical consistent with the strength required for the roof to withstand the weather and the forces resulting from loading, unloading, and operation of the car as part of a train.
Although doors are needed at the ends of such railroad freight cars to protect the motor vehicles carried inside, it must be possible to open the doors to provide ample clearance for loading and unloading the cars, and it would be desired to do so without the open doors being in the way of locomotives or cars on adjacent tracks.
While it is necessary for a person to be able to climb to upper vehicle-carrying decks in such a car during the process of loading vehicles onto the car or unloading them from the car, it is otherwise undesirable for access to the upper decks to be available.
At most times it is desired to limit entry of air, which may include smoke and airborne dust of types which may be corrosive or abrasive and thus easily able to damage the surface finish of newly-manufactured motor vehicles. This is important particularly because it takes a significant amount of time for paint and other protective coatings to reach to their maximum toughness and hardness.
What is needed, then, is an improved railroad freight car which is easily adjustable to serve for carrying a maximum number of motor vehicles of differing sizes and for providing ample protection of such motor vehicles against pilferage and against damage from the elements.